Testing apparatus for fuze timing devices



Dec. 2l, 1954 E. M. MONAT-r 2,697,344

TESTING APPARATUS FOR FUZE TIMING DEVICES Filed May 5, 1954 2 Sheets-Sheet l INVENTOR EUGENE M. MCNATT ATTORNEYS Dec. 2.1,- 1954 E. M. MNAT't TESTING APPARATUS FOR FUzE TIMING DEVICES 2 Sheets-Sheet 2 Filed May 5, 1954 EUGENE M. MCA/Arr a/W Q /3 wm ATTORNEYS United States Patent() TESTING APPARATUS FOR FUZE TllVIlNG DEVICES Eugene M. McNatt, Tulsa, Okla., assgnor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application May s, 1954, serial No. 427,896

11 Claims. (Cl. 73-5) (Granted under Title 35, U. S. Code (1952), sec. 266) The present invention relates generally to testing apparatus and, more particularly, to apparatus for testing timing devices that are subjected to spin forces while operating.

To prevent muzzle bursts and protect personnel and equipment, a delay mechanism is used in influence actuated projectile fuzes such as, for example, the radio proximity fuze. The firing circuit in a fuze of this type usually includes a triggering device in the form of a thyratron tube which becomes conductive when a signal voltage of predetermined magnitude is applied to its control grid. A squib connected in the plate circuit of the thyratron is ignited when the thyratron conducts. Ignition of the squib initiates detonation of the explosive charge carried by the projectile. A satisfactory form of delay mechanism that has been used extensively in proximity fuzes consists of a conductor short-circuiting the squib and means for removing the short circuit upon the elapse of a predetermined time after the firing of the projectile. After removal of the short circuit the fuze is in the completely armed condition and thereafter, when the thyratron becomes conductive, the current in the thyratrons plate circuit can tlow through the squib, igniting the latter.

The timer sometimes used for this delay mechanism is a mechanical clock. In a rotating projectile, the clock is designed to start after setback and is operated by centrifugal force generated by the projectile rotating at high speed. After the elapse of a predetermined operating time, the clock releases a plunger in the delay mechanism which is thrown outwardly by spin forces thereby breaking the short circuiting conductor and arming the fuze. The operating time of this delay mechanism must be determined accurately in order to eliminate any possibility of premature ignition of the squib or failure to arm the fuze within the desired time.

It is an object of the present invention to provide means for accurate testing of spin operated timing mechanisms.

It is a further object to provide means for rapid testing of spin operated devices of the type that are sometimes used as delay mechanisms in fuzes for rotating projectiles.

Other objects and many of the attendant advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Fig. l is a vertical section of the testing apparatus of the present invention, some parts being shown in elevation;

Fig. 2 is a plan view, on a reduced scale, of the testing apparatus shown in Fig. l;

Fig. 3 is a section taken on line 3 3 of Fig. l;

Fig. 4 is a section taken on line 4 4 of Fig. l;

Fig. 5 is a section taken on line 5 5 of Fig. l; and

Fig. 6 is a section taken on line 6 6 of Fig. 1.

Briefly, the invention comprises a support for the spin operated delay mechanism and means for rotating the support at a speed approximating that of a rotating projectile thereby simulating the actual operating conditions of the delay mechanism. An electric circuit is completed through parts of the support at the instant the clock in the delay mechanism is started and is arranged to be interrupted by the plunger released by the delay mechanism when its operating time has elapsed. The circuit controls the power to an external timing clock so ICC that the length of time the latter runs is eratng time of the delay mechanism.

Referring to Fig. 1, the reference numeral 10 is applied to a base of insulating material, partially shown, which supports a housing 11 in which a delay mechanism to be tested is inclosed. The housing 11 has a ange 12 that is attached to a llange 13 on the base 10 by screws 14, only one of which is shown. The upper part of the housing 11 is recessed to provide a shoulder 16 for supporting a top 18 on the housing. A pair of lugs 20 is provided on the outer surface of the top 18. Each lug is engaged by an L-shaped bracket 24 fastened to the housing 11 by screws 26, thereby holding the top 18 on the housing.

The top 18 is provided with a central aperture 28 which has a shoulder 30. A plate 32 of insulating material having an aperture 34 is seated in the aperture 28 abutting the shoulder 30. A second plate 36, also made of insulating material and having an aperture 37 aligned with aperture 34, is supported above the top 18 by posts 38 and screws 40 which extend through the posts and engage threads provided in the top 18. The apertures 34 and 37 are large enough in diameter to loosely receive a plunger 44. Two spaced collars 46 and 48am carried on the plunger 44. The lower collar 46 rests against the plate 32, whereas the upper collar 48 is provided with a set screw 50 so that it may be xed on the plunger 44, and a spring 52 is interposed between collars 46 and 48 to urge the plunger 44 upwardly. As shown in Fig. 1, with the plunger 44 in its uppermost position, the collar 48 rests against the plate 36. A nut 54 is threaded on the upper end of the plunger 44 and a knob 55 of insulating material is screwed onto the end of the plunger above the nut. A soldering lug 56 is mounted between the nut 54 and the knob 55 so that an electrical connection can be made to the plunger 44, and a contact bead 57 is provided on the lower end of said plunger.

A shaft 60, adapted to be rotated by an electric motor or similar means (not shown), extends into the housing equal to the op- 11. The lowermost end of the shaft 60 is mounted in a` ball bearing 62 which is received in a recess formed by an upstanding flange 64 on the supporting plate 66 to permit rotation of the shaft 60 with respect to said supporting plate. A shouldered recess 68 is provided in the lower end of shaft 60 into which a collar 70 is press fitted. The collar 70 has an aperture for tightly receiving a contact pin 72 having a pointed end 73. An externally threaded sleeve 74, having an aperture 75 through which the contact pin 72 extends, is screwed into a threaded aperture 76 in the plate 66 and projects below said plate. A small cup 78 adapted to contain mercury 80 for making electrical contact with the pin 72 is screwed onto the projecting portion of the sleeve 74. The plate 66 may be held stationary in a desired manner, for example, by attachment to the base 10. An electrical connection can be made to the plate 66 by a solder lug 82 held in contact with the plate by a screw S4 threaded thereinto.

A delay mechanism is mounted on the upper end of shaft 60. The delay mechanism used in rotating projectiles comprises a generally circular housing 86 made up of separable sections and a base 87 of larger external diameter than housing 86, thereby providing a shoulder 88. The base 87 has external threads 89 and a llange 90. The base also has a threaded recess 9 1. This arrangement permits ease of assembly of the delay mechanism into a projectile.

The delay mechanism 85 to be tested is received in a cup-like fitting 92 mounted on the shaft 60. A cylin drical shell 93 having an inturned flange 94 abutting a shoulder 95 provided on the tting 92 surrounds the latter for a purpose that will become clear hereinafter. The fitting 92 is provided with a central boss 92 and a hole 96 spaced from said boss to accommodate a rod 97 having a key 98 formed on one end thereof. The key 98 is received in a keyway 99 in the flange 90 of the delay mechanism being tested. The delay mechanism 85 lits relatively snugly in the fitting 92 with the base 87 and llange 90 contacting the bottom of the fitting and the key 9S extending into the keyway 99 to prevent rotation of the delay mechanism with respect to the tting.

A cylindrical sleeve 100 of conducting material fits snugly around the housing 86 of delay mechanism 85. A sector shaped contact mount 101 of conducting material is fitted between a ilat side 101 of the housing 86 and the sleeve 100. A band 102 of spring material is received in a circumferential groove 103 in the sleeve 100 and is bifurcated adjacent one end 102 to receive the reduced portion 104 of a pin 104' that extends through apertures 105 and 106 in sleeve 100 and contact mount 101, respectively, and into a recess 107 in housing 86 to hold said sleeve, mount and housing in assembled relationship. A vertical groove 108 is provided in the flat side of contact mount 101, and a contact 109 is pivotally mounted in the groove on a pin 110, a notch 114 being provided in the upper end of said contact. The contact 109 also has a sloping face 116 adapted for engagement with the bottom of the groove 108 when the lower part of the contact is swung outwardly.

Sleeve 100 is provided near its upper end with an internal shoulder 120 defining a recess in which rests a disk 121 of insulating material. The disk 121 has an upstanding rim 122 to which a flat spring contact 123 is fastened by screws 124. The contact 123 is provided with upper and lower contact elements 125 and 125', respectively, and has an upturned lip 126 adapted to be engaged by a locking cam 127 mounted on a headed pin 128 rotatably carried in an aperture provided in the disk 121. The pin 128 extends into the housing of delay' mechanism 85 and releasably engages a part of the clock mechanism (not shown) to lock said clock mechanism until the timing test begins. When released from the lip 126 of contact 123 in a manner to be described hereinafter, the cam 127 swings outwardly due to spin forces, thereby turning the shaft 128 and starting the clock mechanism housed in the delay mechanism. A resilient L-shaped contact 129 having a contact element 130 is also fastened to disk 121, by a screw 131 and a small protuberance 132 press fitted into an aperture 132 in said disk. The depending portion of L-shaped contact 129 extends through an aperture 134 in disk 121 and has its lower end fitted in the notch 114 in the contact 109. A cap 140 is engaged over the fitting 92 to restrain the delay mechanism S and the contact assembly from excessive vertical motion. The cap 140 is fastened to the tti'ng 92 by a bayonet joint including slots 142 in said cap and pins 144 on said fitting. A spring spider 146 having a central aperture 14S is provided in the top of the cap 140 and has spring elements 150 which Contact the upper edge of the cylindrical sleeve 100 to urge the sleeve downwardly against the shoulder 88 on the delay mechanism housing.

ln assembling the apparatus for testing, a spin operated delay mechanism 85 to be tested in inserted in the sleeve 100 with the spring pressed pin 104 engaging in the apertures 105 and 106, and in the recess 107. The pin 104 holds the delay mechanism S5 and the sleeve 1.00 in proper relative position with the contact 109 aligned with a recess 160 in the housing 86 from which a plunger 162, forming a part of the delay mechanism, is released and projected. fEhe disk 121 is carried on the sleeve 100 so that the lower end of contact 129 is in position to be engaged by the notch 114 in contact 109. This assembly of the sleeve 100, contact mount 101, and the delay mechanism 85 is then inserted into the fitting 92 with the flange 90 resting on the bottom of the fitting and the key 98 extending into keyway 99, to prevent rotation of the delay mechanism 85 with respect to the fitting 92. The cap 140 is inserted in place and locked by the bayonet connection including slots 142 and pins 145%. With the cap 140 in place spring elements 150 of spider 146 press on the edge of sleeve 100 to restrain the delay mechanism 85 from any appreciable vertical motion in the fitting 92. At this point, the top 1S is fastened on the housing 11 with the plunger 44 extending through the aperture 148 in cap 140. Electrical connections 152 and 154 are made between the external clock 156 and the power source 15S. The shaft 60 is then brought up to the desired rotational speed.

After the shaft 60 reaches the desired speed the plunger 44 is depressed, moving contact element 125 into engagement with element 130. This releases the cam 127 and starts the timer in the delay mechanism 85. The electric clock 156 is simutaneously actuated since, with the plunger 44 depressed, a circuit can be traced from the clock 156 through `the plunger, Accmtact's 123, 129 and 109, contact mounting 101, the housing of delay mechanism 85, the fitting 92, shaft 60, contact 22, and mercury 80, to a power source 158. The pivotally mounted contact 109 is designed with a greater mass above shaft 110 than below it so that the spin forces urge said contact into continuous engagement with the'contact 129. After the operating time of the delay mechanism has elapsed, the plunger 162 released by said mechanism is thrown outwardly by spin forces and strikes the bottom part of pivotal Contact 109 thereby opening the circuit and stopping the external timing clock 156.

Obviously many modifications and variations of lthe present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. Apparatus for determining the operating period of a spin operated delay mechanism comprising, a timing clock, a source of power for said clock, a rotatable shaft, means for mounting said spin operated delay mechanism on said shaft whereby the mechanism is adapted to be rotated by the shaft thereby simulating the operating conditions of said delay mechanism, and means for completing an electric circuit between said clock and said power source, said last-named means including a movable contact arranged to be actuated by said spin operated delay mechanism to open said electric circuit upon the elapse of the operating period of said mechanism.

2. Apparatus for determining the operating period of a spin operated delay mechanism comprising, a timing clock, a source of power for said clock, an electric circuit interconnecting said source of power and said clock, a rotatable shaft, a fitting on said shaft for receiving said delay mechanism whereby the mechanism is adapted to be rotated by the shaft thereby simulating the operating conditions of the mechanism, and a movable contact carried adjacent said fitting and connected in said electric circuit, said movable contact being arranged to be actuated by said spin operated delay mech- `anism to open said electric circuit upon the elapse of the operating period of said mechanism.

3. Apparatus for determining the operating period of a spin operated delay mechanism comprising, a timing clock, a source of power, an electric circuit interconnecting said source of power and said clock, a rotatable shaft, a fitting on said shaft for receiving said delay mechanism, means on said fitting for engaging said mechanism whereby the mechanism is arranged to be rotated by the shaft thereby simulating the operating conditions of the mechanism, and a movable Contact carried adjacent said fitting and connected in said electric circuit, said movable contact being arranged to be actuated by said spin operated delay mechanism to open said electric circuit upon the elapse of the operating period of said mechanism.

4. Apparatus for determining the operating period of a spin operated delay mechanism comprising, a timing clock, a source of power, an electric circuit interconnecting said source of power and said clock, a rotatable shaft, a fitting on said shaft for receiving said delay mechanism, means on said fitting for engaging said delay mechanism whereby the mechanism is arranged to be rotated by the shaft thereby simulating the operating conditions of the mechanism, a first movable contact mounted adjacent said delay mechanism and connected in said circuit, means in engagement with said first contact for starting said delay mechanism, means for moving said first contact thereby simultaneously starting said timing clock and said delay mechanism, and a second movable contact adjacent said clock and connected in said electric circuit, said second contact being arranged to be actuated by said spin operated delay mechanism to open said electric circuit upon the elapse of the operating period of said mechanism.

5. In an apparatus for determining the operating period of a spin operated time delay mechanism, a rotatable shaft, means for making an electrical connection to said shaft, means carried on said shaft for receiving said delay mechanism whereby the mechanism is arranged to be rotated by the shaft thereby simulating the operating conditions of the delay mechanism, a movable contact carried adjacent said delay mechanism, said movable contact being electrically connected to said shaft, a fixed contact mounted adjacent said delay mechanism and adapted to be rotated therewith, said movable contact being arranged to be releasably held in engagement with said fixed contact as said shaft rotates, and means for simultaneously making an electrical connection to said fixed contact and beginning the operation of the delay mechanism, said delay mechanism including means for moving said movable contact out of engagement with said fixed contact when the timing operation of said delay mechanism is completed.

6. In an apparatus for determining the operating period of a spin operated time delay mechanism, a rotatable shaft, means for making electrical connection thereto, a fitting on said shaft, said delay mechanism being received in said fitting and adapted to be rotated with said shaft thereby simulating the operating conditions of the mechanism, a pivotally mounted contact carried adjacent said delay mechanism and adapted to be rotated therewith, said contact being electrically connected to said shaft, a fixed contact arranged to be releasably engaged by said pivotally mounted contact while said shaft rotates, a movable contact adjacent said fixed contact, and means for simultaneously moving said movable contact into engagement with said fixed contact and beginning the operation of said delay mechanism, said delay mechanism including means for moving said pivotally mounted contact out of engagement with said fixed contact when the timing operation of said delay mechanism is' completed.

7. In an apparatus for determining the operating period of a spin operated time delay mechanism, a rotatable shaft, means for making electrical connection to said shaft, a fitting carried on said shaft, said delay mechanism being received in said fitting for rotation with said shaft thereby simulating the operating conditions of the mechanism, means for retaining the delay mechanism in said tting, a pivotally mounted contact carried adjacent said delay mechanism and adapted to be rotated therewith, said contact being electrically connected to said shaft, a fixed contact arranged to be releasably engaged by said pivotally mounted contact as said shaft rotates, a movable contact adjacent said fixed contact, and means for simultaneously moving said movable contact into engagement with said fixed contact and beginning the operation of said delay mechanism thereby providing a closed circuit between said shaft and said movable contact, said delay mechanism including means for moving said pivotally mounted contact out of engagement with said fixed contact when the timing operation of the delay mechanism is completed thereby opening said circuit.

8. In an apparatus for determining the operating period of a spin operated time delay mechanism of the type which releases a plunger upon completion of said operating period, a rotatable shaft, means for making an electrical connection to said shaft, a fitting carried on said shaft for receiving said delay mechanism whereby the delay mechanism is arranged to be rotated by said shaft thereby simulating the operating conditions of said delay mechanism, a contact block carried adjacent said delay mechanism, said contact block being provided with a slot, a contact pivotally mounted in said slot and positioned in the path of the plunger released by the delay mechanism, said pivotally mounted contact being electrically connected to said shaft, a fixed contact carried adjacent said contact block, said pivotally mounted contact being arranged to releasably engage said fixed contact when said shaft rotates thereby providing a closed circuit between said shaft and said xed contact, and means for simultaneously making an electrical connection to said fixed contact and beginning the operation of the delay mechanism.

9. In an apparatus for determining the operating period of a spin operated time delay mechanism of the type which releases a plunger upon completion of said operating period, a rotatable shaft, means for making an electrical connection to said shaft, a fitting on said shaft for receiving said delay mechanism whereby said delay mechanism is arranged to be rotated by said shaft thereby simulating the operating conditions of said delay mechanism, a contact block carried adjacent said delay mechanism, a contact pivotally mounted on said block and positioned in the path of the plunger released by the delay mechanism, a fixed contact carried adjacent said contact block, said pivotally mounted contact being adapted to releasably engage said fixed contact when said shaft rotates thereby providing a closed circuit between said shaft and said fixed contact, a movable contact adapted to be actuated to engage said fixed contact, a locking cam adapted to be released by said movable contact for starting the operation of said delay mechanism, and means for moving said movable contact thereby simultaneously making electrical connection to said fixed contact and releasing said locking cam, said plunger being expelled by spin forces to move said pivotally mounted contact out of engagement with said fixed contact when the timing operation of the delay mechanism is completed thereby opening said circuit.

10. In an apparatus for determining the operating period of a spin operated time delay mechanism of the type which releases a plunger upon completion of said operating period, a rotatable shaft, means for making an electrical connection to said shaft, a fitting on said shaft for receiving said delay mechanism whereby said delay mechanism is arranged to be rotated by said shaft thereby simulating the operating conditions of said delay mechanism, a contact block carried adjacent said delay mechanism, a contact pivotally mounted on said block and positioned in the path of the plunger released by the delay mechanism, a fixed contact carried adjacent said contact block, said pivotally mounted contact being arranged to releasably engage said xed contact when said shaft rotates, a movable contact adapted to be actuated to engage said fixed contact, a releasable locking cam for starting the operation of said delay mechanism, said locking cam being held in the locking position by said movable contact, and a plunger for moving said movable contact thereby simultaneously making electrical connection to said fixed contact and releasing said locking cam.

1l. In an apparatus for determining the operating period of a spin operated time delay mechanism having a mechanical timer and a plunger released by said delay mechanism and adapted to be expelled by spin forces acting on said delay mechanism, a rotatable shaft, means for making electrical connection to said shaft, a fitting carried on said shaft and adapted to receive said delay mechanism whereby said delay mechanism will be rotated with said shaft thereby simulating the operating conditions of said delay mechanism, a mounting block adjacent said delay mechanism, said mounting block being provided with a slot aligned with the path of said plunger, a contact pivotally mounted in said slot and electrically connected to said shaft, a xed contact carried adjacent said pivotally mounted contact and adapted to be engaged by said pivotally mounted contact when said shaft is rotating thereby completing a circuit between the shaft and the fixed contact, a movable contact arranged to be moved into engagement with said fixed contact, said movable contact having a lip, a locking cam for starting the timer in said delay mechanism, said cam being held in the locking position by said lip, and a plunger for moving said movable contact into engagement with said fixed contact after said shaft is rotating, thereby simultaneously making electrical connection to said contact and releasing said locking cam.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,568,404 Junghans Ian. 5, 1926 2,343,452 Gibbs Mar. 7, 1944 

